CODEWITHSUNDEEP
javascriptamazon-web-servicesaws-lambdaaws-sdk
kn_pavan
kn_pavan

Reputation: 1618

How to determine if a AWS Lambda function exists

I am new to AWS SDK for JavaScript. I need to check if a Lambda function exists before I trigger execute on it.

I tried the following:
Each time I make a lambda.getFunctionConfiguration() using Function name I have to execute. If it returns an Error, the function doesn't exist. If I get meta, I continue with execution.

I feel this is not a cleaner way to handle this. Is there any other way to check if Lambda exists with the name?
Thanks in advance.

Upvotes: 2

Views: 3310

Answers (2)

Paul T. Rawkeen
Paul T. Rawkeen

Reputation: 4114

Here is how to check if function exists with listFunctions() SDK method (proposed by helloV) in more async way.

const {Lambda} = require('aws-sdk');
const lambda = new Lambda({apiVersion: '2015-03-31'});

const lambdaExists = async (fName, marker = null) => {
    try {
        const {Functions, NextMarker} = await lambda
            .listFunctions({
                Marker: marker || '',
                MaxItems: 50
            })
            .promise();

        const exists = Functions.map(({FunctionName}) => FunctionName).indexOf(fName) !== -1;

        return exists || NextMarker;
    } catch (e) {
        // Handle with care
        console.log(e.toString());
        return e;
    }
};

Function returns true if function name is found in current iteration or NextMarker (string) if not. Iterations end when there is no NextMarker provided in received response.

Note: This function is a generic representation of possible way of solving the issue. Not fully tested in real conditions and could need some corrections to be used in your code.

Upvotes: 0

helloV
helloV

Reputation: 52393

You can use ListFunctions JavaScript API and check if the lambda function is in the output.

listFunctions(params = {}, callback) ⇒ AWS.Request

Returns a list of your Lambda functions. For each function, the response includes the function configuration information. You must use GetFunction to retrieve the code for your function.

Corresponding CLI: aws lambda list-functions

Upvotes: 2

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